In preparation for Michigan's statehood, part of Michigan Territory was formed intoWisconsin Territoryin 1836. Two years later, the western portion was split off to
becomeIowa Territory. The south-eastern part of Iowa Territory became Iowa, the
29th state in the union, on 28 December 1846, by which point 44 counties had been
created.

Counties continued to be created by the state government until 1857, when the last
county,Humboldt County, was created.

One of the most significant days in Iowa county history was January 15, 1851, on
which 49 counties were created.

The Iowa Constitutionof 1857, which is still in effect today, states that counties
must have an area of at least 432 square miles (1,120). No county can be reduced
below that size by boundary changes.

However, exceptions to this rule were granted, as ten counties have areas below this
size, but the Constitution deals with total area. The smallest county (Dickinson)has a land area of 381 sq miles, while the largest (Kossuth county) has an area 973
square miles.Polk Countyis the most densely populated county and contains the state's
capital and largest city,Des Moines, Iowa.